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DeathPhoenix22DeathPhoenix22
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feat: Support 8 directions AStar pathfinding, closes #1213
Co-authored-by: Jean-René Lavoie <>
1 parent 6c00330 commit 641b614

7 files changed

Lines changed: 310 additions & 10 deletions

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‎fxgl-entity/src/main/java/com/almasb/fxgl/pathfinding/Pathfinder.java‎

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@@ -7,6 +7,7 @@
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package com.almasb.fxgl.pathfinding;
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import com.almasb.fxgl.core.collection.grid.Cell;
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import com.almasb.fxgl.core.collection.grid.NeighborFilteringOption;
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import java.util.List;
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@@ -22,10 +23,25 @@ public interface Pathfinder<T extends Cell> {
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*/
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List<T> findPath(int sourceX, int sourceY, int targetX, int targetY);
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/**
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* Empty list is returned if no path exists.
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*
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* @return a list of cells from source (excl.) to target (incl.)
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*/
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List<T> findPath(int sourceX, int sourceY, int targetX, int targetY, NeighborFilteringOption neighborFilteringOption);
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/**
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* Empty list is returned if no path exists.
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*
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* @return a list of cells from source (excl.) to target (incl.) while ignoring busyCells
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*/
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List<T> findPath(int sourceX, int sourceY, int targetX, int targetY, List<T> busyCells);
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/**
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* Empty list is returned if no path exists.
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*
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* @return a list of cells from source (excl.) to target (incl.) while ignoring busyCells
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*/
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List<T> findPath(int sourceX, int sourceY, int targetX, int targetY, NeighborFilteringOption neighborFilteringOption, List<T> busyCells);
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}

‎fxgl-entity/src/main/java/com/almasb/fxgl/pathfinding/astar/AStarPathfinder.java‎

Lines changed: 56 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -6,8 +6,14 @@
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package com.almasb.fxgl.pathfinding.astar;
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import com.almasb.fxgl.core.collection.grid.Cell;
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import com.almasb.fxgl.core.collection.grid.NeighborFilteringOption;
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import static com.almasb.fxgl.core.collection.grid.NeighborFilteringOption.*;
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import com.almasb.fxgl.pathfinding.CellState;
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import com.almasb.fxgl.pathfinding.Pathfinder;
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import com.almasb.fxgl.pathfinding.heuristic.Heuristic;
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import com.almasb.fxgl.pathfinding.heuristic.ManhattanDistance;
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import com.almasb.fxgl.pathfinding.heuristic.OctileDistance;
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import java.util.*;
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@@ -18,11 +24,20 @@ public final class AStarPathfinder implements Pathfinder<AStarCell> {
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private final AStarGrid grid;
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private final Heuristic<AStarCell> defaultHeuristic;
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private final Heuristic<AStarCell> diagonalHeuristic;
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private boolean isCachingPaths = false;
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private Map<CacheKey, List<AStarCell>> cache = new HashMap<>();
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public AStarPathfinder(AStarGrid grid) {
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this(grid, new ManhattanDistance<>(10), new OctileDistance<>());
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}
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public AStarPathfinder(AStarGrid grid, Heuristic<AStarCell> defaultHeuristic, Heuristic<AStarCell> diagonalHeuristic) {
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this.grid = grid;
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this.defaultHeuristic = defaultHeuristic;
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this.diagonalHeuristic = diagonalHeuristic;
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}
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public AStarGrid getGrid() {
@@ -46,11 +61,21 @@ public List<AStarCell> findPath(int sourceX, int sourceY, int targetX, int targe
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return findPath(grid.getData(), grid.get(sourceX, sourceY), grid.get(targetX, targetY));
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}
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@Override
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public List<AStarCell> findPath(int sourceX, int sourceY, int targetX, int targetY, NeighborFilteringOption neighborFilteringOption) {
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return findPath(grid.getData(), grid.get(sourceX, sourceY), grid.get(targetX, targetY), neighborFilteringOption);
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}
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@Override
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public List<AStarCell> findPath(int sourceX, int sourceY, int targetX, int targetY, List<AStarCell> busyCells) {
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return findPath(grid.getData(), grid.get(sourceX, sourceY), grid.get(targetX, targetY), busyCells.toArray(new AStarCell[0]));
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}
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@Override
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public List<AStarCell> findPath(int sourceX, int sourceY, int targetX, int targetY, NeighborFilteringOption neighborFilteringOption, List<AStarCell> busyCells) {
76+
return findPath(grid.getData(), grid.get(sourceX, sourceY), grid.get(targetX, targetY), neighborFilteringOption, busyCells.toArray(new AStarCell[0]));
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}
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/**
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* Since the equality check is based on references,
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* start and target must be elements of the array.
@@ -62,6 +87,20 @@ public List<AStarCell> findPath(int sourceX, int sourceY, int targetX, int targe
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* @return path as list of nodes from start (excl) to target (incl) or empty list if no path found
6388
*/
6489
public List<AStarCell> findPath(AStarCell[][] grid, AStarCell start, AStarCell target, AStarCell... busyNodes) {
90+
return findPath(grid, start, target, NeighborFilteringOption.FOUR_DIRECTIONS, busyNodes);
91+
}
92+
93+
/**
94+
* Since the equality check is based on references,
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* start and target must be elements of the array.
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*
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* @param grid the grid of nodes
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* @param start starting node
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* @param target target node
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* @param busyNodes busy "unwalkable" nodes
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* @return path as list of nodes from start (excl) to target (incl) or empty list if no path found
102+
*/
103+
public List<AStarCell> findPath(AStarCell[][] grid, AStarCell start, AStarCell target, NeighborFilteringOption neighborFilteringOption, AStarCell... busyNodes) {
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if (start == target || target.getState() == CellState.NOT_WALKABLE)
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return Collections.emptyList();
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@@ -75,10 +114,12 @@ public List<AStarCell> findPath(AStarCell[][] grid, AStarCell start, AStarCell t
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}
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}
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Heuristic<AStarCell> heuristic = (neighborFilteringOption.is(FOUR_DIRECTIONS)) ? defaultHeuristic : diagonalHeuristic;
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// reset grid cells data
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for (int y = 0; y < grid[0].length; y++) {
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for (int x = 0; x < grid.length; x++) {
81-
grid[x][y].setHCost(Math.abs(target.getX() - x) + Math.abs(target.getY() - y));
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grid[x][y].setHCost(heuristic.getCost(x, y, target));
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grid[x][y].setParent(null);
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grid[x][y].setGCost(0);
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}
@@ -92,7 +133,7 @@ public List<AStarCell> findPath(AStarCell[][] grid, AStarCell start, AStarCell t
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boolean found = false;
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while (!found && !closed.contains(target)) {
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for (AStarCell neighbor : getValidNeighbors(current, busyNodes)) {
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for (AStarCell neighbor : getValidNeighbors(current, neighborFilteringOption, busyNodes)) {
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if (neighbor == target) {
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target.setParent(current);
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found = true;
@@ -101,16 +142,18 @@ public List<AStarCell> findPath(AStarCell[][] grid, AStarCell start, AStarCell t
101142
}
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if (!closed.contains(neighbor)) {
145+
int gCost = isDiagonal(current, neighbor) ? diagonalHeuristic.getWeight() : defaultHeuristic.getWeight();
146+
int newGCost = current.getGCost() + gCost;
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if (open.contains(neighbor)) {
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int newG = current.getGCost() + 10;
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if (newGCost < neighbor.getGCost()) {
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107-
if (newG < neighbor.getGCost()) {
108151
neighbor.setParent(current);
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neighbor.setGCost(newG);
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neighbor.setGCost(newGCost);
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}
111154
} else {
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neighbor.setParent(current);
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neighbor.setGCost(current.getGCost() + 10);
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neighbor.setGCost(newGCost);
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open.add(neighbor);
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}
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}
@@ -165,10 +208,15 @@ private List<AStarCell> buildPath(AStarCell start, AStarCell target) {
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* @param busyNodes nodes which are busy, i.e. walkable but have a temporary obstacle
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* @return neighbors of the node
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*/
168-
private List<AStarCell> getValidNeighbors(AStarCell node, AStarCell... busyNodes) {
169-
var result = grid.getNeighbors(node.getX(), node.getY());
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private List<AStarCell> getValidNeighbors(AStarCell node, NeighborFilteringOption neighborFilteringOption, AStarCell... busyNodes) {
212+
var result = grid.getNeighbors(node.getX(), node.getY(), neighborFilteringOption);
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result.removeAll(Arrays.asList(busyNodes));
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result.removeIf(cell -> !cell.isWalkable());
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return result;
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}
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218+
private boolean isDiagonal(Cell current, Cell neighbor) {
219+
return neighbor.getX() - current.getX() != 0 && neighbor.getY() - current.getY() != 0;
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}
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}

‎fxgl-entity/src/main/java/com/almasb/fxgl/pathfinding/heuristic/Heuristic.java‎

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/*
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* FXGL - JavaFX Game Library. The MIT License (MIT).
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* Copyright (c) AlmasB (almaslvl@gmail.com).
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* See LICENSE for details.
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*/
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package com.almasb.fxgl.pathfinding.heuristic;
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9+
import com.almasb.fxgl.core.collection.grid.Cell;
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11+
/**
12+
* @author Jean-René Lavoie (jeanrlavoie@gmail.com)
13+
*/
14+
public abstract class Heuristic<T extends Cell> {
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public static final int DEFAULT_WEIGHT = 10;
17+
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private final int weight;
19+
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public Heuristic() {
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this(DEFAULT_WEIGHT);
22+
}
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24+
public Heuristic(int weight) {
25+
this.weight = weight;
26+
}
27+
28+
public abstract int getCost(int x, int y, T target);
29+
30+
public int getWeight() {
31+
return weight;
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}
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}

‎fxgl-entity/src/main/java/com/almasb/fxgl/pathfinding/heuristic/ManhattanDistance.java‎

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/*
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* FXGL - JavaFX Game Library. The MIT License (MIT).
3+
* Copyright (c) AlmasB (almaslvl@gmail.com).
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* See LICENSE for details.
5+
*/
6+
7+
package com.almasb.fxgl.pathfinding.heuristic;
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9+
import com.almasb.fxgl.core.collection.grid.Cell;
10+
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/**
12+
* @author Jean-René Lavoie (jeanrlavoie@gmail.com)
13+
*/
14+
public class ManhattanDistance<T extends Cell> extends Heuristic<T> {
15+
16+
public ManhattanDistance() {
17+
super();
18+
}
19+
20+
public ManhattanDistance(int weight) {
21+
super(weight);
22+
}
23+
24+
@Override
25+
public int getCost(int x, int y, T target) {
26+
return (Math.abs(target.getX() - x) + Math.abs(target.getY() - y)) * getWeight();
27+
}
28+
29+
}

‎fxgl-entity/src/main/java/com/almasb/fxgl/pathfinding/heuristic/OctileDistance.java‎

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/*
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* FXGL - JavaFX Game Library. The MIT License (MIT).
3+
* Copyright (c) AlmasB (almaslvl@gmail.com).
4+
* See LICENSE for details.
5+
*/
6+
7+
package com.almasb.fxgl.pathfinding.heuristic;
8+
9+
import com.almasb.fxgl.core.collection.grid.Cell;
10+
11+
/**
12+
* @author Jean-René Lavoie (jeanrlavoie@gmail.com)
13+
*/
14+
public class OctileDistance<T extends Cell> extends Heuristic<T> {
15+
16+
private static final int DIAGONAL_WEIGHT = (int)(Math.sqrt(2) * 10.0);
17+
private static final int DIAGONAL_FACTOR = DIAGONAL_WEIGHT - 10;
18+
19+
public OctileDistance() {
20+
super(DIAGONAL_WEIGHT);
21+
}
22+
23+
public OctileDistance(int weight) {
24+
super(weight);
25+
}
26+
27+
@Override
28+
public int getCost(int x, int y, T target) {
29+
int dx = Math.abs(x - target.getX());
30+
int dy = Math.abs(y - target.getY());
31+
32+
if(dx == dy) {
33+
return (dx + dy) * 10;
34+
}
35+
if(dx < dy) {
36+
return DIAGONAL_FACTOR * dx + 10 * dy;
37+
}
38+
return DIAGONAL_FACTOR * dy + 10 * dx;
39+
}
40+
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}

‎fxgl-entity/src/main/java/module-info.java‎

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exports com.almasb.fxgl.particle;
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exports com.almasb.fxgl.pathfinding;
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exports com.almasb.fxgl.pathfinding.astar;
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exports com.almasb.fxgl.pathfinding.heuristic;
2627
exports com.almasb.fxgl.pathfinding.maze;
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exports com.almasb.fxgl.physics;
2829
exports com.almasb.fxgl.physics.box2d.dynamics;

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